A conventional, known parking assistance device uses a ranging sensor or an in-vehicle camera to recognize the environment around the vehicle, and recognizes the parking space or calculates the parking route based on the recognition result (see, for example, PTL 1). The parking assistance device of PTL 1 detects the empty space of a parking space formed in a parking lot and predicts a plurality of patterns of leaving route for leaving from the detected empty space. In addition, it is disclosed that a leaving route is selected from the plurality of patterns based on their difficulty levels, and guidance of a forward or reverse parking method is given as the parking method for leaving in the selected leaving route.